Andy Smith
Mine action specialist
 
Developing face and eye protection for HD  
 


Picture of AVS face protection and the workshop in which they were made

“Start from where you are”, is a fairly obvious constraint. So, when first thinking of providing affordable face and eye protection for deminers, I started by looking at what was already being used. UN groups in Cambodia and Mozambique wore safety spectacles designed for use in an industrial workshop. Never more than 1mm thick, they were made of polycarbonate and provided about the same level of protection as sunglasses. The British NGO MInes Advisory Group (MAG) were wearing combat helmets with short polycarbonate visors that were rather complex (12 parts in each hinge) and the HALO Trust deminers were wearing long 5mm thick polycarbonate visors which they had made at LBA, a factory in UK.

MAG and HALO armour

The MAG supervisors often wore sunglasses instead of the heavy helmet. The HALO visor provided the greatest protection in terms of surface area and, mounted on a welding mask head-frame, was far more practical to wear than a heavy helmet. So the HALO visor became my starting point. HALO deminers said it distorted vision, made them feel that they could not breathe, misted up and gave them headaches, but their bosses said they always complained but still wore it.

I knew that their deminers often wore it raised and frequently wore it over a tea-towel to shade their head. I also knew that it cost over $100 and that the price was stopping others from trying it. The 5mm thick polycarbonate sheet that it was made from was cheap, so why was it so expensive? I went to the factory in UK and was told that it needed silk covered heated moulds, special ovens and it took a long time to make each visor – but they were not making them at the time so I could not see the process. No surprise there. I had not concealed the fact that I was hoping to develop something that might hurt their business interests.

cold_pressed face protection

So my first visor designs gave a similar coverage to the HALO visor but were made very cheaply without moulds and without an oven in a process I could give to a small workshop anywhere in the world. I made a press from a car jack and pressed the material into shape. The deminer looked through a flat plane to limit distortion and there was an upward facing vent over the mouth to aid ventilation. A ‘turnover ‘at the top prevented it being scratched easily if put down on its face. The face bolted to the head-frame in a fixed position to prevent the visor being raised and a simple cap shielded the head and neck. At the same time Clark Hulley (then an engineering student at Warwick University) made cold-pressed safety spectacles from 5mm polycarbonate for the supervisors – a design that is wonderfully simple and easy to make but is not being used anywhere (despite many groups today wearing expensive goggles that do not have 5mm thick lenses, so do not meet the requirements of the International Mine Action Standards).

I took my cold-pressed visors to test with HALO in Cambodia, which may have been a mistake. At that time I did not know just how 'close' their Director was to the LBA factory in UK. HALO made two straw filled dummies and put one of their visors on one, my visor on the other – then they sent me away.

Testing with HALO

I asked to be able to film from 500m – there was a good place – but I was not allowed. It was the expert's job, not mine, and he alone knew what he was doing. The disarmed mine was refilled with plastic explosive and positioned with no one allowed to watch - but he did take the picture above. After the crack, the HALO supervisor went forward alone and came back with my visor – so neither the set-up nor the result was reliably photographed. My visor was broken, heat rippled, and very severely burned. I did not even see the HALO visor. But I had no explanation for the visor damage so I went away to rethink the cold-pressed approach to making visors.

More than 100 tests later – most of which have been properly controlled – I know what happened. Either the visor was placed on top of the explosive charge deliberately, or the dummy fell forward accidentally so the visor rested on top of the charge. The only time that polycarbonate has been burned like that is when it has been in direct contact with the explosive charge. I also know that many 'experts' do not admit ignorance, so it is possible that the HALO man did not know that the effects of military grade plastic explosive detonating can be much fiercer than would have been the case with TNT, so the explosion was not representative of a mine blast.

Back at Warwick an engineering student, Paul Sutton, had a bright idea. If moulds are too difficult to make in a small workshop, why not heat-form the material without using moulds – letting them form under their own weight in what is called a catenary curve? I have lost touch with Paul – a regret because he was both bright and right. With no specialist oven on the campus, our attempts to heat-form visors using a paint-drying oven failed, but Clark Hulley managed to form smaller curves in my domestic oven, so showing that the principle was sound and also discovering the critical temperature range. But there was no money to buy a specialist oven - and in any case, the cost of an oven would prevent any local businesses in a post-conflict region being interested in a free technology transfer.

The oven had to be big enough to allow heat to circulate all around a formed visor, have a fan that effectively circulated the air and spread the heat evenly, and be temperature controlled to within a degree or two. Too much heat and the moisture inside the polycarbonate ‘boiled’ in interesting ways.

I went to Zimbabwe to find a potential manufacturer, build an oven, perfect some racks that would hold the polycarbonate and let it take a natural curve, then make some examples and go on to Angola for a series of blast tests with the UN and friendly INGOs. I knew nothing about ovens but I was good with my hands, so I wanted to try.

the oven for visor making

The visor jig

taking out a visor

My oven was the shell of an old safe that I lined, insulated, fitted with lights, a fan, oven glass in the door, and 4kw heating elements under a raised firebrick floor. Apart from the temperature probes which I had brought with me, every part of it was improvised and scavenged from local scrap yards. This oven was still in use fifteen years later (when I last saw it).

My visors were better than HALO’s, having no mould marks and no forced curvature that could build in stresses that would make the visor shatter in an impact. They passed three blasts tests in Angola, two of which were set up properly and I was able to record fully. I was not permitted to be present for the third and doubt that it actually happened – but the INGO involved reported that the visors had ‘passed’ whatever tests they had actually conducted. It is worth mentioning that I had no authority to conduct my testing or to make my many field visits. They were tolerated as long as I accepted a pseudo-military authority that was often blindly ignorant. With no military background myself, everyone outranked me and many EOD specialists enjoyed scoring points over a presumed novice. By that time, I had been a deminer and had considerable experience but never in quite the same context, (every mined area being different) so I did not argue. When in the field, I still defer to those who have the responsibility for managing the risks. And by being respectful, if seemingly stupid, I have often learned far more than I would have done by arguing. My patience was rather more strained when I got a letter from LBA, the makers of HALO’s visors, telling me that HALO had told them what I was doing. They accused me of stealing their design and threatened legal action. My visor was a different size, had a different curve and was made in an entirely different way. It was also a 'not for profit' endeavour that only made sense because they were charging too much for their offering - and it was important that deminers had eye protection. My response was, perhaps understandably, a little sarcastic. I should have just ignored them.

The basic blast visor was easy enough to make but the supply of welding mask head-frames to Zimbabwe was fraught by import restrictions and taxes. Also, these head-frames are adjusted using a ratchet that has a very limited life. With Matthew Chambers, I used off-cuts of body armour materials and some polycarbonate ‘wings’ to make a Velcro fastening head-frame with a washable sweatband over the forehead. By silk-screening a logo onto the top of the visor before forming it we found that the ink burned in and became permanent. With a simple draw-string bag, and a disposable scratch-guard,  the product was ready for more blast testing – which I did first in Mozambique and then in Afghanistan.

the scratch-guard after a blast test

The picture shows a visor with head-frame and the way that the scratch-shield stopped most of the tiny fragments thrown by an anti-personnel blast mine and the visor beneath was unmarked. This does not mean that the visor could safely have been made thinner because the scratch shield was pressed against the visor face and some of the strikes penetrated it but were stopped in the thicker material behind. Polycarbonate is special because its polymer chains are randomly aligned and this allows it to flex very quickly. The shock of being struck by an expanding blast-front is so fast that most materials would shatter but untreated polycarbonate will usually distort and bounce back. The visors do stop or deflect many fragments, but not all. If the fragments ejected by the explosion are travelling too fast or are too hot, the polycarbonate simply flows aside to let them pass. Their good performance against blast forces and relatively poor performance against fragments explains why I have always called these 'blast visors', not 'fragmentation visors'.

field trials in Afghanistan

After more blast tests and field trials (like the one shown above in Afghanistan), the basic blast visor caught on and the Zimbabwe manufacturer has supplied ROFI and ForceWare with the visors that they sell for many years.

In 1999, my ‘technology transfer’ was over but I remained friendly with the team in Zimbabwe. I made them a website and have continued making new designs of equipment for them from time to time. My desire to see visors manufactured in other regions was overtaken by new demands on my time, but my designs were out there for anyone to use. The old Warwick University crew tried in Cambodia, and sold their own designs locally. The field trials and final parts of my work had been done with US government funding so the donor owned my detailed reports on how to make things easily. I knew that they would put them aside but that did not matter. If I can do it in my garage and then guide the transfer to another country, it is not rocket science.

My improved visor design

I returned to visor design after ten years and made a lighter and more comfortable model – shown above – which I transferred to the same Zimbabwe factory. But they charge too much so the old version is still the one I see most often when travelling around. At the same time, I improved the head-frame with a double strap on the back of the head, and my revised visor face allowed for a comfortable fitting on broader heads. This should have been done long before but I had needed a break in order to see the obvious.

polycarbonate mask visor

Then the ROFI mask came out and disappointed me (I had advised on its design), so I made a polycarbonate version. That’s me in the middle, wearing it in a Sri Lankan minefield. If I do not wear it, I cannot ask anyone else to. I am also wearing a solar powered cooling system there – which did not work well enough to take further. The vented visor was better than the ROFI mask, but ‘keep it simple’. I have often travelled with a half-visor (shown on the left below) – and people have frequently offered to buy it. It is light and leaves the nose and mouth clear for easy breathing and voice communication.

vented visor design

But if you want full face coverage and ventilation, the even simpler vented visor in the middle above achieves the same ventilation as a mask with less complexity. I was asked for this by Handicap International in Mozambique, so I made one quickly. The bolts by the jaw have smooth dome heads on the inside but should be made of nylon. Anyway, despite the visor being vented and the visor face being fixed to the head-frame, you cannot stop deminers from pushing the whole visor back on their heads as shown on the right above.

demining goggles

Raised visors were the reason I finally got the International Standards changed to allow the wearing of 5mm polycarbonate goggles as the minimum required protection. Unfortunately, no one was actually making goggles with a 5mm lens at the time. To produce these cheaply (without expensive moulds) was a challenge. I took the  rubber frame from Chinese goggles with a 1.5mm lens and was able to get 5mm lenses with a step-down at the edge made, but I needed Matthew Chambers with his computer controlled router and the forming process was fraught. I did try to do it in Zimbabwe (without enough time or money) but failed to leave a sustainable method behind. Not a real problem. The cold-pressed spectacle style lens designed by Clark Hulley in 1996 (above right) could be made by anyone with a car jack and a jig-saw.

Visor making in the workshop

The last thing I did (always unpaid) for the company in Zimbabwe was make a vacuum tank and moulds able to heat and mould ABS plastic helmets on which to mount visors (bottom centre in the picture above). I think they have continued with it. The workers made me an ‘honorary grandfather’ and presented me with the traditional Shona stick and knives. I believe that this was to say thank you because they had jobs. I thank them for having helped me to do something worthwhile - and making me continue to learn. They really are good people who have to work incredibly hard to scrape a living in a difficult country.

I know that some of my more unusual visor designs have sold because I have seen them in use but the management at the Zimbabwe company has never told me about their sales. In fact, they have not spoken to me since I agreed to help others set up visor manufacture in Colombia several years ago (the Colombians did not follow up because I was far too fussy about quality). And I have not offered my Zimbabwean friends any further assistance since they started manufacturing armour that they know I despise. I do understand that they are a commercial company that has survived the collapse of Zimbabwe’s economy by selling whatever the customer wants. Leaving aside the supply of riot control equipment, this has involved making a lot of peculiar body armour to the customer’s specifications – and you often know that the customer must be a chair polisher who will never have to wear it. When the armour is just too big and clumsy, well the customer knows best, but there must be a limit and that comes when the armour is too small.

HALO Armour - worn by the Halo Trust deminers and the visiting royals

If the 'Saints' studied their own accident record they could not justify continuing to use this minimalist design – which only ever seemed 'good enough' when others were using no body armour at all. The HALO armour varies a little in size but only covers about half of the frontal body and has no collar to catch blast coming from below. My opinion aside, the accident record clearly indicates that the continued use of this armour has led to unnecessary injuries. I cannot help wondering if it is coincidental that after the change of director at HALO someone suddenly realised that there were cheaper sources of blast visor than those made by LBA in UK? Almost 20 years on, I hear that some HALO deminers are finally wearing visors made in my oven. Funny old world.

Be aware that Quality Control (QC) has always been an issue that I cannot address because I give my visor and other designs with no strings. When I am involved in establishing production as I did in Zimbabwe, Quality Assurance checks are built-in and QC is conducted. How well that continues after I leave is outside my control. My original goal was to have lots of places producing PPE for use nearby but that may not have been entirely realistic when working with heat-formed polycarbonate. The skill involved in heat-forming visors is honed by regular practice so it may be better that one company is constantly busy rather than have several companies making irregular batches and competing to cut corners on price. But if anyone wants to make good blast visors or eye-protection for their country/region, I will always  answer questions honestly and try to assist. However, I will never make a Heath Robinson oven and visor forming jigs for anyone ever again. That does not imply regret – it is just that I am no longer prepared to set my hair on fire welding inside an improvised oven. At my age, I have given my quota of sweat and blood to face and eye protection.

See also Blast visor maintenance and UV and Blast goggles or blast visors? For a more complete story of my work in HD and HMA, click here.

Acknowledgements

The following people provided practical help in my eye and face-protection work: Clark Hulley, Matthew Chambers, Matthew Smith, Christopher Marizani, Cosmos Mutemba, Trevor Thomsen, retired Brigadier John Hooper, Paul Sutton, Mark Tebbutt, Keith Byng, and Dominic Gooding. Many deminers and demining managers have also helped to get things tested and sometimes offered design advice. Thanks are also due to retired Colonel George Zahaczewsky from US ARMY CECOM NVESD who gave deminer protection the same priority as I did.

 

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